This section provides background information related to the present disclosure which is not necessarily prior art.
The trend of more stringent future CO2 legislations is accelerating the pace of the industry in adopting the engine downsizing strategy. For a downsized engine to maintain the same vehicle's performance, the engine needs to be boosted either by turbocharging or supercharging. It has been observed that boosted engines have a higher propensity in running into an abnormal combustion phenomena referred to in the literature as pre-ignition, which can result in high noise levels or damage to the engine. One hypothesis of the causes of pre-ignition is the presence of oil in the combustion chamber.
Another issue from the presence of oil droplets in the combustible mixtures is that they can result in the formation of particulates as a combustion byproduct. Due to potential health concerns, more stringent legislations are being developed, which may mandate expensive on-board exhaust filtration systems if proper measures cannot be developed to control oil contents in the combustion chamber.
One source of combustion chamber oil is from crankcase ventilation. The crankcase ventilation system typically includes an oil separation system to remove oil from the recirculated blowby gases. Due to the demand to improve oil separation, oil separation systems have evolved from a single-stage passive system to the current two-stage design. Active systems have also been demonstrated.
The present disclosure regards a passive two-stage oil separation system.